Among the existing mobile communications technologies, Long Term Evolution (LTE), a long term evolution of a universal mobile telecommunications system (UMTS) technical standard formulated by 3GPP, was officially approved and initiated at Toronto 3GPP TSG RAN#26 in December, 2004. Orthogonal Frequency Division Multiplexing (OFDM), multiple-antenna MIMO (Multiple-Input Multiple-Out-put) and other key transmission technologies are introduced in an LTE system, which significantly increases a spectrum efficiency and a data transmission rate (an uplink peak rate can reach 50 Mbit/s, and a downlink peak rate can reach 100 Mbit/s), and supports multiple bandwidth allocations (for example, including: 1.4 MHz, 3 MHz, 5 MHz, 10 MHz, 15 MHz and 20 MHz, etc.), thereby making spectrum allocation more flexible, and significantly improving a system capacity and coverage. In addition, LTE wireless network architecture becomes more flattened, a system time delay is reduced, and a networking cost and a maintenance cost are lowered.
In LTE R12, a small cell is introduced. The small cell is a low-powered wireless access node, and can work at a licensed or unlicensed frequency spectrum. In general, the small cell has a coverage area of 10-200 m. In contrast, a coverage area of a macrocell may reach several kilometers. The small cell integrates a femtocell, a picocell, a microcell and distributed wireless technologies. The small cell may be used indoors or outdoors, and in a practical application scenario, the small cell is much smaller than the macrocell. Generally, the small cell can only cover an area of ten-meter indoor space or two-kilometer outdoor space.
An objective achieved by LTE-A (LTE-Advanced) is to support a downlink peak rate 1 Gbit/s and an uplink peak rate 500 Mbit/s. In order to satisfy this demand, a transmission bandwidth needs to reach 100 MHz. However, in practice available spectrum resources that are continuous and reach the foregoing bandwidth rarely exist. Therefore, LTE-Advanced uses Carrier Aggregation (CA) Technology to aggregate multiple component carriers (CC), thereby achieving a high-bandwidth transmission. A Release 8 LTE carrier supports a maximum bandwidth of 20 MHz. Therefore, LTE-Advanced supports five 20 MHz CCs at the most.
Based on the CA Technology, available carriers include a primary component carrier (Primary Component Carrier, hereinafter referred to as PCC) and a secondary component carrier (Secondary Component Carrier, hereinafter referred to as SCC). The PCC has a control channel, is capable of cross-carrier scheduling the SCC, and may serve as an initial access carrier, whereas the SCC does not have the control channel, and is subjected to a cross-carrier scheduling by the PCC.
At present, types of a carrier are mainly classified into: an LCT carrier type (Legacy Carrier Type, hereinafter referred to as LCT) and a new carrier type (New Carrier Type, hereinafter referred to as NCT).
The LCT refers to a carrier as defined in LTE Release 8, of which bandwidth is fixed, for example, 1.4 MHz, 3 MHz, 5 MHz, 10 MHz, 15 MHz and 20 MHz.
The NCT refers to a new carrier as defined in LTE Release 12, of which bandwidth is not fixed, with multiple bandwidths provided for choice, and with a part of control signal deleted, thus having a higher frequency spectrum utilization efficiency and a bandwidth flexibility.
According to a fact whether or not the NCT may serve as an initial access carrier, the NCT may be classified into a standalone new carrier type (Standalone New Carrier Type, hereinafter referred to as S-NCT) and a non-standalone new carrier type (Non-Standalone New Carrier Type, hereinafter referred to as NS-NCT), wherein the S-NCT itself includes control information, being a substantive NCT independent of a primary carrier, and may serve as the initial access carrier. Whereas the NS-NCT itself does not include control information, shall be subjected to a cross-carrier scheduling by the primary carrier, and cannot serve as the initial access carrier.
In addition, a trend to diversification appears on an LTE service. At present, service types are classified into the following four types:
an unsolicited grant service (Unsolicited grant service, hereinafter referred to as UGS), which is sensitive to a time delay and a transmission rate but insensitive to an error;
a real-time polling service (Real-time polling service, hereinafter referred to as rtPS), which is mainly used in a video streaming and a video conference, tolerant to a longer time delay, and more demanding for a packet error rate;
a non-real-time polling service (Non-real-time polling service, hereinafter referred to as nrtPS), which may be used for a FTP transmission, with major parameters of measurement including: a packet error rate and a minimum transmission rate. In addition, this service is insensitive to a time delay but is more demanding for a packet error rate than the foregoing two services; and
a best effort service (Best Effort, hereinafter referred to as BE), which is mainly applied to HTTP and Email, having no requirement (less demanding) for a data rate, and having a upper limit to a packet error rate.
Due to diversity of the current carrier bandwidth/type and the service type and the development of the carrier aggregation technology, no effective solution has been proposed in the art regarding how to allocate a carrier to a terminal so as to satisfy a user's various service demands. Therefore, in most cases, it is not good enough to satisfy a user's service demand using a conventional method, for example, carriers configuration (including types of operating carriers in a current system, and a bandwidth of each type of carrier) used only according to a measurement performances of the carriers.